In a recently published paper, Germain Tobar and Fabio Costa attempt to demonstrate mathematically that time travel is possible without creating a paradox. I am in no way qualified to speak to the quality of the math used or explain details of the theory, but here's the practical application, as described in a press release from the University of Queensland:
"Say you travelled in time, in an attempt to stop COVID-19's patient zero from being exposed to the virus. However if you stopped that individual from becoming infected - that would eliminate the motivation for you to go back and stop the pandemic in the first place. This is a paradox - an inconsistency that often leads people to think that time travel cannot occur in our universe. Some physicists say it is possible, but logically it's hard to accept because that would affect our freedom to make any arbitrary action. It would mean you can time travel, but you cannot do anything that would cause a paradox to occur."
However the researchers say their work shows that neither of these conditions have to be the case, and it is possible for events to adjust themselves to be logically consistent with any action that the time traveller makes.
"In the coronavirus patient zero example, you might try and stop patient zero from becoming infected, but in doing so you would catch the virus and become patient zero, or someone else would," Mr Tobar said. "No matter what you did, the salient events would just recalibrate around you. This would mean that - no matter your actions - the pandemic would occur, giving your younger self the motivation to go back and stop it. Try as you might to create a paradox, the events will always adjust themselves, to avoid any inconsistency."
If true, it's possible that details of history have already changed, but the overarching direction of history did not. We wouldn't know that details have changed, of course. How this would play out in other scenarios is beyond me. For example, if I were to time travel back and take my late father to the hospital early on the day he died, he could have survived the heart attack. However, since it was his death that compelled me to go back in time in the first place, does that mean that no matter what I did, he would still die that day? In that case, it's pretty much what we saw in The Time Machine (2002).
As for me, I'm of the uninformed layperson's opinion that entropy is the rule. The past is present and the future doesn't exist. Times arrow can't be reversed because of the Second Law of Thermodynamics, and increasing disorder (expressed in the dissipation of energy as heat) is inevitable and unstoppable. Just because we remember past events and can imagine future scenarios doesn't mean that either actually exist.
An understanding that follows from that, for me, is that the the 'purpose' of life is to disperse energy as heat. As explained in a Scientific American article several years ago:
From the standpoint of physics, there is one essential difference between living things and inanimate clumps of carbon atoms: The former tend to be much better at capturing energy from their environment and dissipating that energy as heat. Jeremy England, a 31-year-old assistant professor at the Massachusetts Institute of Technology, has derived a mathematical formula that he believes explains this capacity. The formula, based on established physics, indicates that when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life.
Congratulations! No matter what you do, as long as you're alive, you're fulfilling the purpose of your existence.
Okay, so maybe that isn't very inspiring. I think it should be liberating, though. As human beings we are meaning-makers. We either generate meaning for ourselves or adopt it from culture and/or religion. Really it's a mix of of those, in differing proportions from person to person. Some think critically about their beliefs, while others outsource it completely to a religion or just go along with culture and upbringing. There are degrees to which we assert control over our worldview and the meaning we generate for ourselves. Since our biological, physical purpose is going to take place no matter what, then everything else is icing on the cake.
This isn't a license to 'sin,' of course. Empathy-based ethics informs us that it's still wrong to betray trust, murder, or otherwise harm others. What it does mean is that we are free to make what we will of our lives, within the boundaries of commitments we have made, and the rule of consideration for others. So, go be a wandering hippy, a scientist, a homemaker, a devout believer, an indefatigable skeptic, or whatever else you want to make of yourself. Be multiple things (because we already are). Make it interesting, or embrace the routine.
The Summer Day
Who made the world?
Who made the swan, and the black bear?
Who made the grasshopper?
This grasshopper, I mean-
the one who has flung herself out of the grass,
the one who is eating sugar out of my hand,
who is moving her jaws back and forth instead of up and down-
who is gazing around with her enormous and complicated eyes.
Now she lifts her pale forearms and thoroughly washes her face.
Now she snaps her wings open, and floats away.
I don't know exactly what a prayer is.
I do know how to pay attention, how to fall down
into the grass, how to kneel down in the grass,
how to be idle and blessed, how to stroll through the fields,
which is what I have been doing all day.
Tell me, what else should I have done?
Doesn't everything die at last, and too soon?
Tell me, what is it you plan to do
with your one wild and precious life?
—Mary Oliver
